Integrated collector storage solar water heater under partial vacuum

Manolis Souliotis, Spiros Papaefthimiou, Yiannis Caouris, Aggelos Zacharopoulos, Patrick Quinlan, Mervyn Smyth

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)
120 Downloads (Pure)


The work focuses on the experimental study of the heat diode mechanism in an Integrated Collector Storage Solar Water Heater (ICSSWH) for domestic applications. The solar device combines a horizontal cylindrical vessel with an asymmetric reflector trough (Compound Parabolic Concentrator e CPC). The cylindrical storage tank comprises two concentric cylindrical vessels: the outer absorbing vessel and the inner storage vessel. The annulus between the cylindrical vessels is partially depressurized and contains a small amount of water serving as Phase Change Material (PCM), which changes phase (mainly at low temperatures) thus producing vapor and creating a thermal diode transfer mechanism from the outer to the inner surfaces of the vessels. Several experimental results, including uncertainty analysis, are demonstrated through diagrams depicting temperature variations, mean daily efficiency and thermal losses coefficient. Additionally results from the variation of the temperature and the total pressure inside annulus are also presented. The results clearly show that the vapor's pressure plays the most important role regarding the thermal performance of the device.
Original languageEnglish
Pages (from-to)991-1002
Number of pages12
Early online date17 Aug 2017
Publication statusPublished (in print/issue) - 15 Nov 2017


  • heat diode
  • Compound Parabolic Concentrator
  • Phase Change Material
  • pressure


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